Like most vehicles having internal combustion engines, motorcycles have starters for starting the engine. Starters are typically electric motors powered by the vehicle battery and include a pinion that drives a starter gear that rotates with the engine. The pinion is commonly mounted for axial movement between a retracted position, where the pinion and gear are disengaged, and an extended position, where the pinion engages the gear. The pinion is typically biased toward the retracted position and is moved toward the extended position by a solenoid.
Some motorcycles include an engine assembly that is separate from the transmission assembly. In these vehicles, a primary drive assembly is commonly utilized to transfer power from the engine crank shaft to an input shaft of the transmission assembly. The primary drive assembly can include a number of suitable power transmission elements, including gearing arrangements, belt and pulley systems, or chain and sprocket systems. Many primary drive assemblies include housings that protect or support the power transmission elements. The housing may also function to contain fluids for lubrication of the power transmission elements.
In some motorcycles utilizing a primary drive assembly, the starter gear is positioned within the primary housing and coupled for rotation with the power transmission elements. In these systems, the starter is commonly mounted to a flange on the transmission housing and is positioned such that the pinion extends through an opening in the primary housing to engage the starter gear.
Due to the need to provide a flange for mounting the starter, the transmission housing can be a very complicated casting. It would be desirable to simplify the mounting of the starter so as to avoid the need for a complicated transmission casting.